The power system short-circuit capacity grows with the increasing of penetration power from wind farm based on doubly-fed induction generator（DFIG）. Thus， it is important to analyze the short-circuit current from wind farm quantitatively in relay setting and breaker switching. Based on the analysis of physical processes following the short-circuit fault of DFIG， the balance circuit of initial fluxes， components of frequencies and the dependent relationship between stator current and rotor current are studied. By solving the flux circuits， an analytic expression and practical calculation method for the short-circuit current are obtained and the perspectives on frequency components， decay time constants， amplitude and initial phase are unified. The practical model simulation results compared with detail model show that the practical model can accurately describe the short circuit current for DFIG.